Making a crystal material in Blender
It eens to me that you should add a little more geometry, make sure the roughness value on your glass shader is the same as your examples and the main difference that I see is the lighting setup. The other person is using some sort of image texture as their light source. A very nice touch. Also, I suggest you turn up your samples so the image isnt so grainy. If you have any questions as to how you can do any of this jut ask